Can you please try these steps
1. In your linux server please goto /opt/site24x7/monagent/conf and delete this 'pl_id_mapper' file.
2. Restart the agent once.
Once restarted will have a clean slate and will be can start over again. If you still have any problems please get in touch with us support at email@example.com we can give you more pinpoint guidance.
Product Manager, Site24x7